Overcoming challenges in WAVE bioreactors without feedback controls for pH and dissolved oxygen



The biopharmaceutical industry is increasing its use of the WAVE Bioreactor for culturing cells. Although this disposable bioreactor can be equipped to provide real-time pH and dissolved oxygen (DO) monitoring and control, our goal was to develop a process for culturing CHO cells in this system without relying on pH and DO feedback controls. After identifying challenges in culturing cells without controlling for pH and DO in the WAVE Bioreactor, we characterized O2 and CO2 transfer in the system. From these cell-free studies, we identified rock rate and rock angle as key parameters affecting O2 transfer. We also identified the concentration of CO2 in the incoming gas and the rate of gas flow into the headspace as key parameters affecting CO2 transfer—and therefore pH—in the disposable culture chamber. Using a full-factorial design to evaluate the rock rate, rock angle, and gas flow rate defined for this WAVE Bioreactor process, we found comparable cell growth and pH profiles in the ranges tested for these three parameters in two CHO cell lines. This process supported cell growth, and maintained pH and DO within our desired range—pH 6.8–7.2 and DO exceeding 20% of air saturation—for six CHO cell lines, and it also demonstrated comparable cell growth and viability with the stirred-tank bioreactor process with online pH and DO control. By eliminating the use of pH and DO probes, this process provides a simple and more cost-effective method for culturing cells in the WAVE Bioreactor. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011